The present invention is directed to a suction roller. The suction roller is used for conveying sheets in a sheet processing machine.
A sheet feeding device is known from DE 33 11 196 C2, in which an alignment cylinder has a suction drawing strip in the vicinity of its front lay marks. The suction drawing strip is used for aligning the lateral edges of sheets. In the course of the transfer of the sheets to a following drum, the start of each sheet is held by grippers, and the front lay marks border the sheet.
DE 23 30 484 C3 describes a suction roller with individual suction rings.
EP 0 846 638 A2 describes a device for mounting a sheet on a suction drum with detents.
The object of the present invention is directed to creating a suction roller.
In accordance with the present invention, this object is attained by providing a suction roller for conveying sheets in a sheet processing machine. The suction roller can be driven at varying circumferential speeds. A portion of its exterior surface projects through a slit provided in a guide element. The suction roller has front lay marks on its circumference and has its own drive motor.
The advantages which can be achieved by the present invention reside, in particular, in that printed sheets can be passed, with their front edges aligned, to a further processing station by use of a single roller. In this case, every sheet is bent only slightly, during its transport to the further processing station by use of a suction roller. During the transfer to the next conveying means, the start of the sheet is free of holding elements or detents.
Furthermore, a great amount of flexibility of the chain of movements of the suction roller is possible because of the suction roller having its own electric motor.